The effects of oxygen partial pressure on the microstructures and photocatalytic property of ZnO nanoparticles

The effects of oxygen partial pressure on the microstructures and photocatalytic activity of ZnO nanoparticles prepared by evaporation–condensation method in a flow of Ar and O2 have been studied by field-emission scanning electron microscopy (FESEM), XRD, XSM800 photoelectron spectrometer (XPS) and UV–Vis spectrometer. The size and shape of ZnO nanoparticles prepared at the oxygen partial pressure (700–800 Pa) show slight difference from that prepared at the oxygen partial pressure ranging from 1500 to 2300 Pa. However, the relative percentage of surface oxygen vacancies decreases from 40.6% (prepared at 700–800 Pa) to 29.3% (2200–2300 Pa) in the condition of similar ratio of Zn atoms to total oxygen species by the qualitative calculation of XPS data. ZnO nanoparticles were examined as photocatalysts for the UV-induced degradation of methyl orange in water solution. The photodegradation results directly demonstrate that the oxygen partial pressure influences the photoactivity of ZnO nanoparticles greatly.